JPS6117046A - Method for determining position of light source in reflected light measuring device - Google Patents

Abstract

PURPOSE:To perform accurate measurement, by providing a specified varying range before and after a measuring surface, moving and positioning light sources so that the peak value of the output of a sensor lies within said range with respect to the measuring surface, thereby reducing the effect of fluctuation of the position of a sample. CONSTITUTION:A measuring surface aperture 10a is formed on the upper surface of a sample table 10. A heat insulating filter 11 is attached to the inner side of the aperture. A plurality of illuminating lamps 12 are arranged under the filter at an equal interval so that the lamps can be moved. A lens 16 is fixed to a cylindrical lens holder 15. The image of light, which has passed the lens 16, is formed on an image forming aperture 17a, which is formed on a sensor attaching plate 17. An interference filter 18, which transmits only the light having a specified wavelength, is provided in front of the attaching plate 17. A sensor 19 arranged at the rear of the plate 17. An incubated chemical analysis slide 20 is mounted on the sample table 10.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a method for positioning an illumination light source used in a reflection densitometer, etc., and more specifically, to a method for positioning an illumination light source used in a reflection densitometer, etc. The present invention relates to a positioning method.

[Prior art]

Reflection density needles are used in various fields, one of which is chemical analysis equipment. This chemical analyzer quantifies test components present in body fluids using chemical analysis slides that develop color through enzymatic or chemical reactions.
This consists of an incubator, a reflection density needle, and a calculation control unit. The incubator is for incubating the chemical analysis slide at a predetermined temperature and degree for a predetermined time in order to sufficiently progress the coloring reaction of the chemical analysis slide, and the reflective density needle is for incubating the chemical analysis slide after the incubation. This is for measuring the color density of slides. The arithmetic and control device calculates the concentration of the test component and controls the incubator by referring to a calibration curve that plots the relationship between the reflection concentration and the concentration of the test component. The chemical analysis slide is composed of a sheet-like measurement element in which a reagent holding layer is coated on a transparent support, and a slide frame that includes a spotting aperture and a photometry aperture and houses the sheet-like measurement element. There is. The structure of the chemical analysis slide and chemical analysis device is described in detail in, for example, Japanese Patent Laid-Open No. 521-21566.

In the reflection densitometer, a plurality of illumination light sources are arranged at four angles with respect to the measurement surface.
It is arranged inclined at an angle of 5 degrees and illuminates the lower surface of the sheet-like measuring element.

The light reflected by this sheet-like measurement element passes through a lens and an interference filter that transmits only light in a specific wavelength range, and enters the sensor, where it is photoelectrically converted. The output of this sensor is converted into a digital value and converted into a concentration value by a microcomputer.

In order to measure the reflection density with high precision, it is necessary to ensure that the sample is correctly set on the measurement surface determined in the design, and if the sample position deviates from the measurement surface, the illumination condition changes. Therefore, the output of the sensor is tabulated and different concentration values are output. Incidentally, in the chemical analysis slide, the sample position slightly fluctuates across the measurement surface due to processing accuracy of the slide frame, deflection of the measurement element due to dropping of the liquid sample, and the like.

We conducted nine different experiments on the relationship between sample position deviation and sensor output, and found that by adjusting the distance between the illumination light source and the sample position, we found that some cases were not affected by sample position deviation and others were greatly affected. I found out that there are cases. Therefore, the present invention was completed based on the discovery that highly accurate measurement can be performed by arranging the illumination light source at a position that is not affected by the displacement of the sample position.

[Purpose of the invention]

Therefore, it is an object of the present invention to provide a method for positioning an illumination light source that can minimize the influence of variations in sample position and perform highly accurate measurements.

[Structure of the invention]

In order to achieve the above object, the present invention determines the range in which the sample position fluctuates before and after the measurement surface, and determines the position of the illumination light source so that the peak of the sensor output falls within this fluctuation range. be.

〔Example〕

FIG. 1 shows a reflected light measuring section incorporated into the chemical analysis apparatus. The sample stage 10 has a measurement surface aperture 10a formed on its upper surface, and a heat shielding filter 11 is attached inside the measurement surface aperture 10a.

Below this heat protection filter 11, a plurality of lighting lamps 1 are provided.
2 are arranged at equal intervals on concentric circles.

Each of these illumination lamps 12 is integrally provided with a lens 12a at its tip, and is held in a lamp holder 13. Further, the illumination lamp 12 is movable within the lens holder 13, and is fixed with screws 14 after position adjustment.

The lens holder 15 has a cylindrical shape, and a lens 16 is fixed therein. The light passing through this lens 16 forms an image on an image forming surface aperture 17a formed in a plate 17 for mounting the sensor. In this sensor installation, an interference filter 18 that transmits only light in a predetermined wavelength range is placed in front of the plate 17, and a sensor 19 is placed behind the imaging plane aperture 17a.

An incubator (not shown) is placed on the sample stage 10.
A chemical analysis slide 20 that has been incubated with is placed thereon. This chemical analysis slide 20 is composed of a sheet-shaped measurement element 21 and a slide frame 22 that houses and holds this measurement element 21.

When measuring the glucose concentration present in a body fluid, such as blood, using the chemical analysis slide 20, a fixed amount of fresh heparinized blood, for example 10 μp, is dropped from a spotting opening formed at the top of the slide frame 22. After this spotting, the chemical analysis slide 20 is incubated at 37° C. for 6 minutes. After the incubation is completed, when the chemical analysis slide 20 is placed on the sample stage 10, the measurement element 21 is illuminated with the illumination lamp 12. The light reflected by the measurement element 21 passes through the lens 16. The light passes through the interference filter 18 and enters the sensor 19, where it is photoelectrically converted.

In this embodiment, the measuring element 21 is mounted 9.5 mm above the lower surface of the slide frame 22. Accordingly, the measurement surface is Q, 5n from the top surface of the sample stage 10.
+ above, and if the measuring element 21 is always on the measuring surface, the illumination conditions are the same, so a correct density value can be obtained. However, the actual sample position changes depending on the machining accuracy of the slide frame 22 or the deflection of the measuring element 21 due to spotting of the liquid sample. Although this change in sample position is 0.2 mm before and after the measurement surface, the density value varies greatly depending on the position of the illumination lamp 12.

FIG. 2 shows the output waveform of the sensor when measuring the reflected light from the white plate used as the reference density value.

The horizontal axis indicates the height (h) from the light source 12 to the sample position, and the range surrounded by the dotted line is the range in which the sample position changes, which in this example is 0.2 mm before and after the measurement surface. Curve A shows the output of the sensor 19 when the distance l between the sample position and the illumination lamp 12 is set short and the sample position is changed in this state, and curve B shows the output when the distance l is medium. The curve C shows the case where the distance β is long. As the illumination lamp 12 is moved within the lamp holder 13 and the distance l is shortened, the curve C changes toward the curve A.

In curve A, the output of the sensor 19 changes significantly downward to the right in the variation range of the sample position, so even if the reflection density is the same, the measurement results vary greatly depending on the sample position. In curve C, since the curve changes greatly upward to the right, as in curve A, variations in the sample position greatly affect the measurement results. Curve B has a peak value within the variation range of the sample position, and therefore is least affected by sample position variation.

Therefore, while moving the illumination lamp 12 within the lamp holder 13, check the output of the sensor 19, find the lamp position where the peak value of the sensor 19 is within the variation range of the i&R position, as shown in curve B, and tighten the screw 14. to fix the illumination lamp 12.

〔Effect of the invention〕

The present invention having the above configuration moves the illumination light source with respect to the measurement surface, finds the lamp position where the peak value of the sensor output occurs within the variation range of the sample position, and positions the illumination light source at this position. Therefore, the influence of fluctuations in the sample position is minimized, and highly accurate measurements can be performed.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of the reflected light measuring section. FIG. 2 is a waveform diagram showing the sensor output when changing the sample position. Process 0... Sample stand 12... Illumination lamp 13... Lamp holder 16... Lens 18... Interference filter 19...
Sensor 20...Chemical analysis slide 21...Measurement element 22...Slide frame.

Claims (1)

[Claims] Reflected light that is obtained by arranging an illumination light source at an angle of 45 degrees with respect to the measurement surface, and measuring the light reflected by a sample located on the measurement surface with a sensor arranged perpendicular to the measurement surface. In the measuring device, a predetermined fluctuation range is set before and after the measurement surface, and the peak value of the output of the sensor is within this fluctuation range.
A method for positioning an illumination light source, characterized in that the illumination light source is positioned by moving the illumination light source back and forth with respect to a measurement surface.